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Drones: Useful Earth observation platform, or an expensive toy?

Commercial drones have undergone a sharp rise in popularity over the past decade. At the beginning of 2015, 133 drones were registered in the US for commercial purposes. By the end of the same year, this number had rocketed to 5,761. With the increasing number of simple, easy to fly, and affordable drones entering the market, the level of interest in their use for a range of potential Earth observation (EO) applications is also rising.

From the pocket sized DJI Spark, measuring just 143 x 143 mm and weighing only 300 grams, to the vastly popular Phantom, with the ability to reach speeds of 45 mph, quadcopters have become somewhat of an everyday feature in modern day life for both professionals and amateurs alike. But these drones represent a very small portion of the overall market, with both hexacopters (6 propeller) and octocopters (8 propeller) beginning to take over contemporary enterprise, as well as the continued use of more traditional fixed wing drones.

Whilst seen by some as an expensive hobby, a fun delivery gimmick, or just a nuisance cluttering up our skies, perhaps the full potential of drones is yet to be utilised. In terms of EO, solely drone based studies have already been carried out to monitor water extent (e.g. Klemas, 2015), map disease (e.g. Hardy et al. 2017), model geomorphology (e.g. Casella et al. 2016), detect pollution (e.g. Capolupo et al. 2014) and even track animals (e.g. van Gemert et al. 2014).

Just like satellites, drones can be equipped with multispectral, hyperspectral, thermal and radar sensors, albeit with lower spectral resolutions. Unlike satellites, drones operate at an altitude below that of persistent cloud cover, removing interference of any such atmospheric disturbances, a problem which often encumbers optical satellite data.

Drone missions are easier to operate on a need-to-acquire basis, a characteristic often unavailable, or more complicated, with other types of remotely sensed data. This increased temporal resolution and access to cloud-free imagery, when used in conjunction with the superior global coverage and array of spectra available from satellite data, provide the potential for EO applications to be carried out across a range of scales, not possible when considering solely drones or satellites alone.

Group of future pilots undertaking drone training in Colombia.

This â€˜sensor synergyâ€™ is an idea we are currently exploring for the monitoring of agriculture for the EcoProMIS Project weâ€™re involved in Colombia. Partnering with Nuba Aerospace, a series of specifically designed vertical take-off and landing (VTOL) drones have been created, combining the benefits of vertical take-off and landing of rotary platforms with the flight speed and coverage of fixed wing drones.

However, a great deal of expertise is needed in both the commercial and recreational operation of drones, and as such there are a number of rules and regulations one must follow. Colombia is a global pioneer in drone regulations with those wishing to fly drones required to take certified training courses, have mandatory insurance, be in constant communication with the air traffic control of the nearest airport, and submit flight plans 15 days before every drone flight. Whilst thorough, the regulations have been criticised by some as unachievable and unenforceable.

Whilst in the UK drone regulations were updated on the 30th May 2018, which require all owners of drones weighing 250 grams or more to register with the Civil Aviation Authority (CAA), as well as for drone pilots to take an online safety test. Further restrictions have also been placed on where pilots can fly their drones. Failure to follow these updates or complete the necessary paperwork could see pilots land themselves a fine of up to Â£2,500. This is in response to a reported 24% rise in incidents involved drones over the last year, including a number of close encounters with commercial planes.

Yet the outlook is positive for the involvement of drones as tools for remote sensing. With the continued improvement of satellite sensors and the addition of more accessible drone data, it is an exciting time for contemporary EO, with possible applications of such devices ever growing.